Apparatus and method for delivering transport characteristics of multimedia data

ABSTRACT

There are provided a method and apparatus for delivering transport characteristics of multimedia data. According to an aspect of the present invention, transport characteristics of media data that can be divided in a unit of a Media Processing Unit (MPU) are created in a unit of a predetermined number of MPUs, the created transport characteristics and a flag indicating presence or absence of the created transport characteristics are inserted into the media data, and the resultant media data is delivered. Accordingly, by using transport characteristics in units of media data unit groups, each media data unit corresponding to a short time length, it is possible to effectively control Quality of Service (QoS) in a dynamically changing transport environment, like a mobile network.

PRIORITY

This application claims the priority under 35 U.S.C. §119(a) to KoreanApplication Serial No. 10-2012-0077856, which was filed in the KoreanIntellectual Property Office on Jul. 17, 2012, the entire content ofwhich is hereby incorporated by reference.

JOINT RESEARCH AGREEMENT

The present disclosure was made by or on behalf of the below listedparties to a joint research agreement. The joint research agreement wasin effect on or before the date the present disclosure was made and thepresent disclosure was made as a result of activities undertaken withinthe scope of the joint research agreement. The parties to the jointresearch agreement are 1) SAMSUNG ELECTRONICS CO., LTD. and 2)UNIVERSITY-INDUSTRY COOPERATION GROUP OF KYUNG HEE UNIVERSITY

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a method and apparatus fordelivering multimedia data packets in a broadcasting and communicationsystem, and more particularly, to a method and apparatus for deliveringtransport characteristics of multimedia data in units of MediaProcessing Unit (MPU) groups for Quality of Service (QoS) control whenmultimedia content constituted with one or more MPUs is serviced in anetwork environment dynamically changing over time in a broadcasting andcommunication system that supports a multimedia service based on anInternet protocol.

2. Description of the Related Art

IEEE802.16 (WIMAX), IEEE802.11e (WiFi TXOP), 3rd Generation PartnershipProject Universal Mobile Telecommunication System (3GPP UMTS), and 3GPPLong Term Evolution (LTE) have a function of reserving resources andguaranteeing the reserved resources. Real-time multimedia services use aresource reservation protocol in order to guarantee QoS. As arepresentative example, Internet Engineering Task Force (IETF) hasdefined parameters required for reserving network resources between userterminals and a content server in a Resource reSerVation Protocol (RSVP)which is a resource reservation protocol.

FIG. 1 illustrates a process of specifying data with a Variable BitRate(VBR) as double leaky bucket parameters.

VBR traffic is expressed as double leaky buckets using four parametersRg, Rp, Bp, and B included in Traffic specification Tspec. Rg is anaverage bitrate, and no overflow occurs when data is stored in a bufferalthough the bitrate of the data momentarily exceeds the bitrate Rg. Arequired buffer size is designated as Bg in advance. Likewise, a peakbitrate Rp is also reserved. Under an assumption that a peak bitrate ismaintained during a period in which a packet is transported, a buffersize Bp for a peak bitrate Rp can be set to the maximum size of ServiceData Unit (SDU). The maximum size of SDU is generally expressed asMaximum Transfer Unit (MTU).

Table 1 shows four double leaky bucket parameters used in variousprotocols.

TABLE 1 3GPP IETF RSVP, UMTS IEEE802.11e IEEE802.16 & ‘tspec’ (WIMAX)LTE MPEG-4 OD ATM Rp p Min. Maxi- avgBitrate PCR reserved mum trafficrate bit- rate (4B) Bp M SDU size Maxi MAX_AU_SIZE CDVT mum SDU size Rgr Max. Guar- AverageBitRate SCR sustained anteed traffic rate bit- rate(4B) Bg b Maximum k * bufferSizeDB BT Latency Maxi- mum SDU

Accordingly, creating transport characteristics of multimedia usingdouble leaky bucket parameters is effective in view of compatibilitywith other protocols. Generally, the resource reservation protocol isexecuted when a service session for providing a multimedia service isestablished, and it is assumed that while a service is maintained, theprotocol is used by end-to-end systems on a network that transports datawith respect to entire multimedia content. However, end-to-end resourcereservation for a service cannot be embodied in general open Internetenvironments. Furthermore, a core network achieves stable broadbandtransmission, however, at or near network end points, a problem mayoccur due to resources sharing between many users. Particularly, in awireless or mobile communication network, a network resource environmentchanges dynamically due to various factors, such as users' migration,interference, or the like.

FIG. 2 illustrates Signal to Interference plus Noise Ratio (SINR)measured for 10 minutes in an IEEE802.16 network environment.

The Moving Picture Experts Group (MPEG) is doing standardization of MPEGMedia Transport (MMT) technology, and the MMT technology providestransport characteristics in a unit of asset through Asset DeliveryCharacteristics (ADC) in order to embody a function of reserving aresource for a multimedia service and guaranteeing the reserved resourceand a function of constructing transport characteristics of multimediadata in a dynamic network environment and transmitting/receiving thetransport characteristics.

In the MMT technology, an asset is logical data entity, and constructedwith one or more Media Processing Units (MPUs). The asset is a greatestdata unit to which configuration information and transportcharacteristics of multimedia are applied.

The ADC is used to guarantee QoS upon transmission of MMT assets, andthe ADC specifies parameters for a specific transmission environment andparameters for QoS. By using the ADC, a service provider can configure anetwork resource in consideration of media characteristics required fortransmission when reserving a resource according to network environmentconfiguration. However, in a dynamic network environment where SINRvaries in real-time, it is difficult to guarantee the amount of resourcereserved using existing RSVP or the like when a service session started.Furthermore, in a mobile environment, when a user moves into thecoverage area of another base station, resource reservation should beagain performed. For these reasons, when a resource is reserved in orderto guarantee QoS of a multimedia service in a dynamic networkenvironment, it will be effective to reserve a resource in units ofshorter lengths than in resource reservation for entire content.Accordingly, there is a need to propose a method of inserting additionalinformation for controlling QoS for MPUs in a unit of a MPU groupincluding a plurality of MPUs each of which is a small unit constitutingmedia content.

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

An aspect of the present invention is to provide a method and apparatusfor effectively guaranteeing Quality of Service (QoS) of a multimediaservice by providing transport characteristics of media data that can betemporally divided in a dynamic network environment.

Means for Solving Problems

According to an exemplary embodiment of the present invention, there isprovided a method of delivering transport characteristics of multimediadata in a system that supports a multimedia service based on an Internetprotocol. The method includes creating transport characteristics ofmedia data that is dividable in a unit of a Media Processing Unit (MPU),in a unit of a predetermined number of MPUs; and inserting the createdtransport characteristics and a flag indicating presence or absence ofthe created transport characteristics into the media data, anddelivering the resultant media data.

According to another exemplary embodiment of the present invention,there is provided an apparatus of delivering transport characteristicsof multimedia data in a system that supports a multimedia service basedon an Internet protocol. The apparatus includes an encapsulatorconfigured to create transport characteristics of media data that isdividable in a unit of a Media Processing Unit (MPU), in a unit of apredetermined number of MPUs; and a delivery unit configured to insertthe created transport characteristics and a flag indicating presence orabsence of the created transport characteristics into the media data,and to deliver the resultant media data.

Effects

Therefore, according to the exemplary embodiments of the presentinvention, by using transport characteristics in units of media dataunit groups, each media data unit corresponding to a short time length,it is possible to effectively control Quality of Service (QoS) in adynamically changing transport environment, like a mobile network.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a process of specifying data with a Variable BitRate(VBR) as double leaky bucket parameters;

FIG. 2 illustrates Signal to Interference plus Noise Ratio (SINR)measured for 10 minutes in an IEEE802.16 network environment;

FIG. 3 illustrates a structure of a MPEG Media Transport (MMT)encapsulator header according to an exemplary embodiment of the presentinvention;

FIG. 4 is a view for describing an example of using transportcharacteristics for media data delivery between a MMT server and a MMTclient, according to an exemplary embodiment of the present invention;and

FIG. 5 is a flowchart of a method of creating and delivering transportcharacteristics for media data delivery in a MMT server, according to anexemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Hereinafter, exemplary embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings. Termsused in the present disclosure are currently widely used general termsselected in consideration of the functions in the exemplary embodiments;however, they may be changed according to the intention of a user oroperator, the practice, or the like. Thus, it will be appreciated thatterms used in the following exemplary embodiments must be construedbased on definitions disclosed in the present disclosure and if notdefined, the terms must be construed as meanings that are generallyunderstood to one of ordinary skill in the art.

Transport characteristics of media data in a unit of a Media ProcessingUnit (MPU) group proposed in the present disclosure may be generated ina generation (capture or grab) process of content and in anencapsulation process of media data encoded in advance. Here, the MPUgroup represents a data unit including a plurality of MPUs, and a MPUgroup may be constructed with MPUs having the same characteristics (forexample, the same bitrate). A method of using the transportcharacteristics upon transmission is as follows. An exemplary embodimentof the present invention will be, for convenience of description,described based on MPEG Media Transport (MMT) of which the MovingPicture Experts Group (MPEG) is doing standardization, however, thepresent disclosure is not limited to the MMT. A MMT system is dividedinto an encapsulation layer, a delivery layer, and a control (signaling)layer according to its function. Hereinafter, how the individual layersuse transport characteristics will be described.

1) MMT Encapsulation Layer

The MMT encapsulation layer performs a function of generating transportcharacteristics of media data in a unit of a MPU group proposed in thepresent disclosure.

FIG. 3 illustrates a structure of a MPEG Media Transport (MMT)encapsulator header according to an exemplary embodiment of the presentinvention.

A MMT asset constructed with one or more Media Processing Units (MPUs)is a component (for example, a video component or an audio component)constructing media content. Accordingly, each MMT asset includestransport characteristics of media data. The transport characteristicsfor each MMT asset may be used for QoS control, resource reservation,etc. in a process of establishing a session of the corresponding MMTasset using a Resource reSerVation Protocol (RSVP) or the like.Transport characteristics in a unit of a MPU group proposed in thepresent disclosure is added as an identifier for identifying informationthat can be used for delivery and QoS control, using flags regarding oneor more MPU groups constructing a MMT asset.

2) MMT Control Layer

The MMT control layer is in charge of a function of exchanging servicediscovery information, Quality of Experience (QoE) managementinformation, and Digital Rights Management (DRM) information between aserver and a client. When service discovery information is exchanged, aprocess of reserving a network resource for establishing a session maybe performed, and in this case, QoS control such as resource reservationis performed using transport characteristics included in a MMT asset. Asdescribed above, since QoS control based on asset is performed in a unitof entire content, in a dynamic environment, QoS control based on a MPUgroup which is a smaller unit is needed.

3) MMT Transport Layer

The MMT transport layer is in charge of a function of transportingencapsulated media data packets from a server to a client and a function(for example, a cross-layer interface) of exchanging information betweenlayers in a terminal. To do these, the MMT transport layer generatesdelivery packets. The MMT transport layer extracts QoS-relatedinformation that should be included in each delivery packet fromtransport characteristics in order to guarantee QoS of the deliverypacket.

FIG. 4 is a view for describing an exemplary embodiment in whichtransport characteristics of media data generated by the MMTencapsulation layer are used in a media transport service.

Asset delivery characteristics of media data in a unit of a MPU groupproposed in the present disclosure are generated by an encapsulationlayer (E layer) 403 of a MMT server 401 and then inserted into the mediadata in the form of flags. The asset delivery characteristics includesinformation (for example, double leaky bucket parameters;bitstream_descriptor) required for resource reservation, andQoS_descriptor that is included in each delivery packet and indicatesrelative priority of the delivery packet. The bitstream_descriptor istransferred to the control layer (C layer) 405 (406), and thentransferred to a C layer 409 of a client 402 through a signalingprotocol, such as Real-Time Stream Protocol (RTSP) or Session InitiationProtocol (SIP). In the case of QoS_descriptor, if the C layer 405transfers parsed information to a delivery layer (D layer) 404 (407),the D layer 404 may insert the parsed information into each deliverypacket, and then transport the resultant delivery packet to the client402 and an intermediate network system (not shown) through a datachannel. Alternatively, it is also possible to directly access anencapsulation header of data transferred through a path 408, to parsethe corresponding field to acquire information, and then to transportthe acquired information. The above process is performed in units of MPUgroups each corresponding to a shorter time length than an asset.

Hereinafter, syntax and semantics for transport characteristics in aunit of a MPU group according to an exemplary embodiment of the presentinvention will be described in detail.

Syntax for additional information for QoS control and delivery in a unitof a MPU group (or a media data unit, such as Group Of Pictures (GOP),corresponding to a shorter time length than an asset) proposed in thepresent invention and semantics for individual fields are shown in Table2. As seen in Table 2, the names and sizes of the individual fields, andthe kinds of variables specifying the individual fields have beenselected in consideration of the functions in the exemplary embodimentsof the present invention, however, they may be changed according to theintention of a user or operator, the practice, or the like. In thepresent disclosure, the meanings of the individual fields should beunderstood based on the following definitions.

TABLE 2 No. Mne- Of mon- Syntax bits ic MPU_Header( ){    mpu_length;   header_length;    mpu_sequence_number;    number_of_au;    for(inti=0; i<number_of_au; i++){        au_length;    }   private_header_flag;    if(private_header_flag == 1){       private_header_length        private_header    }   MPU_delivery_characteristic_header_flag;   if(MPU_delivery_characteristic_header_flag == 1){       QoS_descriptor( ){           loss_priority;          delay_priority;           class_of_service;          hybrid_sync_indicator;        }        Bitstream_descriptor(){           sustainable_rate;           buffer_size;          peak_rate;           max_MFU_size;           MFU_perid;       }    } } MPU_Payload( )

TABLE 3 Element or Attribute Name Use Description mpu_sequence_numberspecifies sequence number of MPU in a single MMT asset. It isincremented by 1 and will be unique within an MMT asset. number_of_auspecifies the number of AUs in this MPU. au_length specifies length ofeach AU in this MPU private_header_flag indicates that there isprivate_header private_header_length specifies the length ofprivate_header MPU_delivery_characteristic_header_flag indicatespresence/absence of MDC, if the flag is 1, MDC follows the flagloss_priority specifies characteristics regarding packet data loss ofMPU 11: loss priority 0 (Lossless) 10: loss priority 1 (Lossy, Highpriority) 01: loss priority 2 (Lossy, Medium priority) 00: loss priority3 (Lossy, Low priority) delay_priority specifies characteristicsregarding delay sensitivity of MPU 11: high sensitivity: end-to-enddelay <<1 sec (e.g., VoIP, video- conference) 10: medium sensitivity:end-to-end delay approx. 1 sec (e.g., live- streaming) 01: lowsensitivity: end-to-end delay <5~10 sec (e.g., VoD) 00: don't care(e.g., FTP, file download) class_of_service classifies characteristicsof MPU data according to bitstream characteristics 111: The Constant BitRate (CBR) service class shall guarantee peak bitrate at any time to bededicated for transmission of the MPU. This class is appropriate forrealtime services which require fixed bitrate such as VoIP withoutsilence suppression. 110: The Real-Time Variable Bit Rate (rt-VBR)service class shall guarantee sustainable bitrate and allow peak bitratefor the MPU with delay constraints over shared channel. This class isappropriate for most realtime services such as video telephony,videoconferencing, streaming service, etc. 101: The Non-Real-TimeVariable Bit Rate (nrt-VBR) service class shall guarantee sustainablebirate and allow peak bitrate for the MPU without delay constraint overshared channel such as file downloading. 100: The Available Bit Rate(ABR) class shall not guarantee any bitrate, but may report availablebitrate for feedback control. This class is appropriate for applicationswhich can be adaptive to time-varying bitrate such as video streamingwith RTCP feedback. 011: The Unspecified Bit Rate (UBR) class shall notguarantee any bitrate and shall not indicate congestion. This class isappropriate for interactive applications such as Web browsing. UBRservice is equivalent to the common term “best effort service”.hybrid_sync_indicator flag for synchronization, if the flag is 1,synchronization with other MPU shall not be considered, and if it is 0,synchronization with other MPU shall be considered. 1: no dependency. 0:dependent on other MPU for synchronization in hybrid delivery.sustainable_rate The sustainable_rate defines the minimum bitrate thatshall be guaranteed for continuous delivery of the MPU. Thesustainable_rate corresponds to drain rate in token bucket model. Thesustainable_rate is expressed in kilobits of MFU(or MPU) per second.buffer_size The buffer_size defines the maximum buffer size for deliveryof the MPU. The buffer absorbs excess instantaneous bitrate higher thanthe sustainable_rate and the buffer_size shall be large enough to avoidoverflow. The buffer_size corresponds to bucket depth in token bucketmodel. Buffer_size of a CBR(constant bit rate) MPU shall be zero. Thebuffer_size is expressed in kilobits peak_rate The peak_rate definespeak bitrate during continuous delivery of the MPU. The peak_rate is thehighest average bit rate during every MFU period. The peak_rate isexpressed in kilobits of MFU(or MPU) per second. MFU_period The MFUperiod defines minimum period of MFU during continuous delivery of theMPU. The MFU period is expressed in millisecond. max_MFU_size Themax_MFU_size is the maximum size of MFU, which is MFU_period *peak_rate. The max_MFU_size is expressed in kilobits.

As described in Table 3, the sustainable_rate defines the minimumbitrate that shall be guaranteed for continuous delivery of the MPU, thebuffer_size defines the maximum buffer size for delivery of the MPU, thepeak_rate defines peak bitrate during continuous delivery of the MPU,the MFU_period defines the minimum period of Media Fragment Unit (MFU)during continuous delivery of the MPU, and the max_MFU_size defines themaximum size of MFU.

FIG. 5 is a flowchart of a method in which a MMT server createsmultimedia data transport characteristics in units of MPU groups anddelivers the transport characteristics to a MMT client, according to anexemplary embodiment of the present invention.

Referring to FIG. 5, the MMT server creates multimedia data transportcharacteristics that include QoS_descriptor indicating relative priorityfor each delivery packet and Bitstream_descriptor indicating informationrequired for resource reservation in units of MPU groups (501). TheQoS_descriptor and Bitstream_descriptor have been described above withreference to Tables 1 and 2, and accordingly, further descriptionsthereof will be omitted.

Then, the MMT server inserts information indicating presence/absence ofthe created transport characteristics, in the form of a flag, into themultimedia data, also inserts the transport characteristics into themultimedia data, and then, delivers the resultant multimedia data to theMMT client (503). Operation of creating the transport characteristics,inserting them into the multimedia data, and then delivering theresultant multimedia data may be performed by the E layer 403 of FIG. 4.The multimedia data into which the transport characteristics have beeninserted may be transferred to both the C layer 405 and the D layer 404.

Thereafter, the MMT server extracts the QoS_descriptor from thetransport characteristics to deliver the QoS_descriptor to the MMTclient (505), and extracts Bitstream_descriptor from the transportcharacteristics to deliver the Bitstream_descriptor to the MMT client(507). In other words, the MMT server delivers the QoS_descriptor tomanage QoS for the corresponding multimedia service, and delivers theBitstream_descriptor to reserve a resource for the correspondingmultimedia service. The present exemplary embodiment relates to anexample in which the MMT server sequentially performs steps 505 and 507,however, the MMT server may simultaneously perform steps 505 and 507 ormay perform step 507 prior to step 505.

However, the operations or flowchart illustrated in FIGS. 4 and 5 asdescribed above are not intended to limit the scope of the right of thepresent invention. In other words, the operations described above withreference to FIGS. 4 and 5 are examples about how the individual layersoperate, all the operations are not necessarily performed in order toembody the present invention, and also the operations may be performedby other layers unlike the example of FIG. 4.

While the invention has been shown and described with reference tocertain exemplary embodiments thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the invention asdefined by the appended claims and their equivalents.

What is claimed is:
 1. A method of delivering transport characteristicsof multimedia data in a system that supports a multimedia service basedon an Internet protocol, comprising: creating transport characteristicsof media data that is dividable in a unit of a Media Processing Unit(MPU), in a unit of a predetermined number of MPUs; and inserting thecreated transport characteristics and a flag indicating presence orabsence of the created transport characteristics into the media data,and delivering the resultant media data.
 2. The method of claim 1,wherein the transport characteristics include bitstream informationrequired for resource reservation and Quality of Service (QoS)information indicating relative priority for each delivery packet. 3.The method of claim 2, wherein the QoS information includes at least onefield among a first field (loss-priority) specifying characteristicsabout delivery packet loss of MPU data, a second field (delay_priority)specifying characteristics about delay sensitivity of the MPU data, athird field (class_of_service) specifying service characteristics of theMPU data, and a fourth field (hybrid_sync_indicator) for synchronizationwith other MPU data.
 4. The method of claim 2, wherein the bitstreaminformation includes at least one field among a first field(sustainable_rate) defining a minimum bitrate required to be guaranteedfor delivery of MPU data, a second field (buffer_size) defining amaximum buffer size for delivery of the MPU data, a third field(peak_rate) defining a peak bitrate during delivery of the MPU data, afourth field (MFU_period) defining a minimum period of a Media FragmentUnit (MFU), and a fifth field (MFU_size) defining a maximum size of theMFU.
 5. The method of claim 1, further comprising performing resourcereservation and Quality of Service (QoS) control in units of thepredetermined number of MPUs using the transport characteristics.
 6. Anapparatus of delivering transport characteristics of multimedia data ina system that supports a multimedia service based on an Internetprotocol, comprising: an encapsulator configured to create transportcharacteristics of media data that is dividable in a unit of a MediaProcessing Unit (MPU), in a unit of a predetermined number of MPUs; anda delivery unit configured to insert the created transportcharacteristics and a flag indicating presence or absence of the createdtransport characteristics into the media data, and to deliver theresultant media data.
 7. The apparatus of claim 6, wherein the transportcharacteristics include bitstream information required for resourcereservation and Quality of Service (QoS) information indicating relativepriority for each delivery packet.
 8. The apparatus of claim 7, whereinthe QoS information includes at least one field among a first field(MPU_delivery_characteristics_header_flag) indicating presence orabsence of the transport characteristics, a second field (loss-priority)specifying characteristics about delivery packet loss of MPU data, athird field (delay_priority) specifying characteristics about delaysensitivity of the MPU data, a fourth field (class_of_service)specifying service characteristics of the MPU data, and a fifth field(hybrid_sync_indicator) for synchronization with other MPU data.
 9. Theapparatus of claim 7, wherein the bitstream information includes atleast one field among a first field (sustainable_rate) defining aminimum bitrate required to be guaranteed for delivery of MPU data, asecond field (buffer_size) defining a maximum buffer size for deliveryof the MPU data, a third field (peak_rate) defining a peak bitrateduring delivery of the MPU data, a fourth field (MFU_period) defining aminimum period of a Media Fragment Unit (MFU), and a fifth field(max_MFU_size) defining a maximum size of the MFU.
 10. The apparatus ofclaim 6, further comprising a controller configured to perform resourcereservation and Quality of Service (QoS) control in units of thepredetermined number of MPUs using the transport characteristics.